This is a request for a Mentored Patient-Oriented Career Development Award. Over the five years of the award, the candidate will conduct one observational study and two clinical trials of hospital-based interventions to improve drug abuse treatment entry and retention among medicine inpatients. Primary mentorship will be provided by Drs. George Bigelow and Daniel Ford. Additional mentoring and tutorial assistance will be provide by Drs. Maxine Stitzer, Laura Morlock, and Carlo DiClemente. The goals for this career development project are to better understand the role of the medical hospitalization on motivation for treatment and readiness for change and to assess whether clinical interventions can improve subsequent treatment entry and retention. Specific aims are to (1) identify factors within an acute hospitalization episode that influence a person's motivation for and actual entry into treatment. (2) Determine whether hospital-based clinical interventions improve treatment entry and retention upon hospital discharge. (3) Determine whether these interventions effect subsequent health utilization and management of concurrent HIV infection. Three sub-studies will be conducted on a cohort of substance abusing patients admitted to the medicine service at Johns Hopkins Hospital: (a) an observational, longitudinal study of substance abusing medicine inpatients; (2) a randomized clinical trials of peer mentor-structured transitional support and (3) a quasi-experimental study of concurrently administered substance abuse treatment. This program of research and training will provide important information on the acute medical hospitalization for substance abusing patients and how it can best be structured to improve health care and substance abuse outcomes.